The present invention relates to a locking mechanism for sliding doors or windows offering improved security and convenience over those which have been previously available.
Sliding doors and windows are finding wide current architectural usage because they are inexpensive to construct and do not require clearance in the interior of the building. Despite these advantages, they have been an easy point of entry for burglars and other types of criminals. To date, most of the locking mechanisms for sliding glass panels of this type have been primitive and unsatisfactory. Many of these locks can be overcome by simply forcing a pry bar between the door or window and it's casing and applying a moderate amount of force. In view of this well-known weakness, most homeowners adopt the expedient of laying a dowel in the lower track of the sliding panel. While this may discourage the unskilled thief, it is usually not effective against the professional burglar who can often insert a thin bar along the edge of the window and flip the dowel out of the channel. This is especially easy to do if the door has been slightly opened to obtain better ventilation.
Another common security device is a hinged bar across the door. This is attached at one end to the door or window frame while the other end rests in a channel attached to the casing. This bar needs only be lifted from the retaining channel in order to open the door. Once again, enterprising thieves have devised tools and means to accomplish this purpose in a fair number of installations.
Other means which offer a higher degree of security are known, but these are considered by most people to be undesirable from points of complexity, expense, or appearance. There has been a major unfilled need for a highly effective security device for sliding doors or windows that is simple, moderately priced, and does not detract from the esthetic appearance.